MedicalResearch.com Interview with: Michael Sigal PhD Clinical scientist of the Charité -- Universitätsmedizin Berlin Investigator at the Max Planck Institute for Infection Biology  MedicalResearch.com: What is the background for this study? What are the main findings? Response: We have previously found that H. pylori can colonize gastric glands and that in colonized glands the epithelial turnover was increased. We wanted to characterize the mechanisms that control the gland turnover in the stomach. We found that Axin2, a classic Wnt target gene, marks two different subpopulations of cells with stem cell properties, one of which is Lgr5-positive and the other one Lgr5-negative. Both populations are affected by Rspondin 3, that is produced in myofibroblasts right beneath the stem cell compartment. Rspondin is crucial for stem cell signaling and knockout of Rspondin 3 in myofibroblasts results in loss of Lgr5 and Axin2 expression. Once we increased the bioavailability of Rspondin, that now could also interact with cells outside of the stem cell compartment, we noticed that the number of Axin2 positive stem cells dramatically increased. Of interest, only Lgr5-negative cells expanded in number and proliferate more, while the Lgr5-positive cells remained silenced. Infection with Helicobacter pylori leads to an expansion of Axin2-positive cells which is driven by increased expression of Rspondin3. Expansion of the long lived stem cell pool could be an explanation for how H. pylori infection increases the risk for gastric cancer. (more…)